What intermolecular forces are present in #CH_3OH#?

1 Answer
anor277
Jun 23, 2018

Well, you got hydrogen bound to the VERY ELECTRONEGATIVE oxygen atom....

Explanation:

And in such a scenario where hydrogen is bound to a strongly electronegative element, hydrogen bonding is known to occur….a special case of bond polarity...

We could represent the dipoles as...

#H_3C-stackrel(delta^+)O-stackrel(delta^-)H#

And in bulk solution, the molecular dipoles line up...and this is a SPECIAL case of dipole-dipole interaction, #"intermolecular hydrogen bonding"#, the which constitutes a POTENT intermolecular force, which elevates the melting and boiling points of the molecule.

And so we got normal boiling points of...

#CH_4# #;-164# #""^@C#.

#H_3C-CH_3# #;-89# #""^@C#.

#H_3C-OH# #;+64.7# #""^@C#.

#H_3C-CH_2OH# #;+78.5# #""^@C#.

#H-O-H# #;+100.0# #""^@C#.

Of course, dispersion forces operate between all molecules...but these are not the same magnitude as intermolecular hydrogen bonding....

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